An image forming apparatus includes a secondary transfer roller in order to bring an image bearing member such as a transfer belt and a recording medium into press contact with each other and transfer an image onto the recording medium. For example, when a jam occurs or when maintenance is necessary, the press-contact of the secondary transfer roller needs to be released to separate the secondary transfer roller from the transfer belt.
Concerning this point, in a mechanism proposed in JP-A-2006-11184, when a part of a housing is opened, a secondary transfer roller moves following the opening of the part of the housing and separates from a transfer belt.
However, in this technique, mechanisms associated with the part of the housing increases. Therefore, a large force is necessary to open the housing and operability is deteriorated.
To cope with this problem, provision of a lever exclusively used for separating the secondary transfer roller is proposed. FIG. 5 is a diagram of a releasing mechanism for the secondary transfer roller by this related art.
As shown in FIG. 5, in the releasing mechanism in the past, when a release handle 101 is pulled up in a direction of an arrow X, an arm 102 pivots to push down a secondary transfer roller 11 and move the secondary transfer roller 11 along a track A.
However, a large force is necessary when a secondary-transfer-roller-side positioning member 109 climbs over a contact portion 106A of a positioning member 106. As a result, smooth release of the secondary transfer roller 11 cannot be realized.